Allow diff of encrypted files

I am not very sure about the use of "--use-agent" yet, but should do for
now. Also need to configure diff.encrypted.textconv" before it works.
Review: report 0% when total is also 0 hours.
Change generated weekly review summary

My categories and heading needs are slightly different than
Sacha's (even though I copied a lot of them for starting quickly). I
modified the functions to generate a report for myself.
Pick up fix for quantified.el to login first.